Jhbate/add activity

a starting point
I'd like intensity to be on some sort of scale. METs (Metabolic Equivalents) is pretty standard and I see it on exercise machines, and it kind of ranges from about 1 (watching TV) to 10 (jumping rope). Seems like that might be good to use that as a guidline -- it's still self-reported, but at least you have something better than "I worked hard".